If the UIM is in good shape you can clean it and reuse it, I had to replace mine because when I took the throttle body gasket off the plastic of the UIM that surrounds the gasket broke off.
The Dorman UIM is only 64.79 at rockauto.com, DORMAN Part # 615180
If you replace the EGR stovepipe IMO you really do not need the added steel bushing, the EGR gasses should not be a problem with the reduced diameter EGR Stove Pipe.
If you really want that steel bushing you can spend 90.00 and get it from here.
GM Intake Manifold Kit